Semiconductor structure and method for manufacturing the same

ABSTRACT

A semiconductor structure and a method for manufacturing the same are provided. The method comprises following steps. A first silicon-containing conductive material is formed on a substrate. A second silicon-containing conductive material is formed on the first silicon-containing conductive material. The first silicon-containing conductive material and the second silicon-containing conductive material have different dopant conditions. The first silicon-containing conductive material and the second silicon-containing conductive material are thermally oxidized for turning the first silicon-containing conductive material wholly into an insulating oxide structure, and the second silicon-containing conductive material into a silicon-containing conductive structure and an insulating oxide layer.

BACKGROUND

1. Technical Field

The disclosure relates to a semiconductor structure and a method formanufacturing the same.

2. Description of the Related Art

Memory devices are used in storage elements for many products such asMP3 players, digital cameras, computer files, etc. As the applicationincreases, the demand for the memory device focuses on small size andlarge memory capacity. For satisfying the requirement, a memory having ahigh element density is need.

Designers have developed a method for improving a memory device density,using 3D stack memory device so as to increase a memory capacity and acost per cell. However, the scaling limitation of a memory cell size ofthis kind of the memory device is still bigger than 50 nm. It is noteasy to breakthrough the limitation. The performance of the memorydevice may also be limited due to its element material.

SUMMARY

A method for manufacturing a semiconductor structure is provided. Themethod comprises following steps. A first silicon-containing conductivematerial is formed on a substrate. A second silicon-containingconductive material is formed on the first silicon-containing conductivematerial. The first silicon-containing conductive material and thesecond silicon-containing conductive material have different dopantconditions. The first silicon-containing conductive material and thesecond silicon-containing conductive material are thermally oxidized forturning the first silicon-containing conductive material wholly into aninsulating oxide structure, and the second silicon-containing conductivematerial into a silicon-containing conductive structure and aninsulating oxide layer on the surface of the silicon-containingconductive structure and contact with the silicon-containing conductivestructure.

A semiconductor structure is provided. The semiconductor structurecomprises a substrate, an insulating oxide structure, asilicon-containing conductive structure, and an insulating oxide layer.The insulating oxide structure is formed on the substrate. Thesilicon-containing conductive structure and the insulating oxide layerare formed on the insulating oxide structure. At least one of theinsulating oxide structure and the insulating oxide layer has a bird'sbeak profile.

The following description is made with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 to FIG. 4 illustrate a method for manufacturing a semiconductorstructure in one embodiment.

FIG. 5 illustrates a semiconductor device in one embodiment.

DETAILED DESCRIPTION

Embodiments of the present disclosure relate to a semiconductorstructure and a method for manufacturing the same. The semiconductor hasa small feature size and excellent characteristic.

FIG. 1 to FIG. 4 illustrate a method for manufacturing a semiconductorstructure in one embodiment. Referring to FIG. 1, firstsilicon-containing conductive materials 4 and second silicon-containingconductive materials 6 are stacked on a substrate 2. The secondsilicon-containing conductive materials 6 are separated from each otherby the first silicon-containing conductive materials 4. For example, thefirst silicon-containing conductive material 4 has a thickness T1, about20 nm. The second silicon-containing conductive material 6 has athickness T2, about 40 nm.

Referring to FIG. 1, in one embodiment, the substrate 2 is singlecrystal silicon, and the first silicon-containing conductive materials 4and the second silicon-containing conductive materials 6 are singlecrystal silicon formed from the substrate 2 by an epitaxial growth. Forexample, the substrate 2 is single crystal silicon. The firstsilicon-containing conductive material 4 is single crystal siliconformed from the substrate 2 by an epitaxial growth. The secondsilicon-containing conductive material 6 is single crystal siliconformed from the first silicon-containing conductive material 4 by anepitaxial growth. The first silicon-containing conductive material 4 issingle crystal silicon formed from the second silicon-containingconductive material 6 by an epitaxial growth. Therefore, the secondsilicon-containing conductive materials 4 and the secondsilicon-containing conductive material 6 can be single crystal having anexcellent structure and conductivity characteristic. Thus performance ofthe semiconductor structure is improved.

The first silicon-containing conductive materials 4 and the secondsilicon-containing conductive materials 6 are patterned for formingstacked structures 8 as shown in FIG. 2. Referring to FIG. 2, each ofthe stacked structure 8 comprises the first silicon-containingconductive materials 4 and the second silicon-containing conductivematerials 6 stacked alternately. A method for the pattering comprisesremoving a part of the first silicon-containing conductive materials 4and the second silicon-containing conductive materials 6 by an etchingprocess. In one embodiment, the first silicon-containing conductivematerials 4 and the second silicon-containing conductive materials 6have similar materials such as silicon. Thus, the etching process hassubstantially the same etching rate for the first silicon-containingconductive materials 4 and the second silicon-containing conductivematerials 6. Therefore, the etching process can be exactly controlled topatterning the first silicon-containing conductive materials 4 and thesecond silicon-containing conductive materials 6 into a fine profile orhigh aspect ratio. For example, the stacked structure 8 has a width W,about 20 nm. The two adjacent stacked structures 8 has a distance D,about 130 nm, therebetween.

Each of the first silicon-containing conductive materials 4 and thesecond silicon-containing conductive materials 6 are thermally oxidizedfor turning the first silicon-containing conductive material 4 whollyinto an insulating oxide structure 16, and the second silicon-containingconductive material 6 into a silicon-containing conductive structure 18and an insulating oxide layer 20 on the surface of thesilicon-containing conductive structure 18 and contact witch thesilicon-containing conductive structure 18 as shown in FIG. 3. Referringto FIG. 3 the insulating oxide structure 16 and the insulating oxidelayer 20 have a bird's beak profile. For example, the thermallyoxidizing process comprises heating the first silicon-containingconductive materials 4 (FIG. 2) and the second silicon-containingconductive materials 6 placed in an oxygen condition, diffusing oxygeninto the first silicon-containing conductive materials 4 and the secondsilicon-containing conductive materials 6 from the surfaces of which toreact to produce an insulating oxide such as silicon oxide.

In embodiments, the first silicon-containing conductive material 4 (FIG.2) and the second silicon-containing conductive material 6 havedifferent dopant conditions. Thus, under a thermal oxidizing process ofthe same condition, or during the thermally oxidizing the firstsilicon-containing conductive materials 4 and the secondsilicon-containing conductive materials 6 simultaneously, the firstsilicon-containing conductive material 4 and the secondsilicon-containing conductive material 6 have different oxide diffusionrates. In embodiments, the first silicon-containing conductive material4 and the second silicon-containing conductive material 6 have dopantsof different concentrations and the same conductivity type. For example,the first silicon-containing conductive material 4 and the secondsilicon-containing conductive material 6 both have N type dopant, andthe concentration of the N type dopant of the first silicon-containingconductive material 4 is bigger than the concentration of the N typedopant of the second silicon-containing conductive material 6. Forexample, there may be 2-3 orders difference between the concentrationsof the N type dopants of the first silicon-containing conductivematerial 4 and the second silicon-containing conductive material 6.Therefore, the first silicon-containing conductive material 4 has anoxide diffusion rate higher than an oxide diffusion rate the secondsilicon-containing conductive material 6 has. The N-type dopantcomprises a VIA-group element such as P, As etc. Otherwise, the firstsilicon-containing conductive material 4 and the secondsilicon-containing conductive material 6 both have P type dopant. Inaddition, the concentration of the P type dopant of the firstsilicon-containing conductive material 4 is different from theconcentration of the P type dopant of the second silicon-containingconductive material 6. The P-type dopant comprises a IIIA-group elementsuch as B etc. The oxidation situation of the first silicon-containingconductive material 4 and the second silicon-containing conductivematerial 6 can be controlled by adjusting parameters of the oxidizingprocess such as a heating temperature, a heating time, etc.

The insulating oxide layers 20 are removed for forming stackedstructures 22 as shown in FIG. 4. In embodiments, the insulating oxidelayers 20 are removed by using an etching process having an etchingselectivity to an insulating oxide (such as silicon oxide) and asilicon-containing conductive material (such as single crystal silicon).Thus, during the removing the insulating oxide layer 20, a part of theinsulating oxide structure 16 is also removed simultaneously. Theinsulating oxide structure 16 becomes small. Meanwhile, thesilicon-containing conductive structure 18 is not damaged substantially.For example, the etching process comprises a dry etching method or a wetetching method.

FIG. 5 illustrates a semiconductor device in one embodiment. Referringto FIG. 5, in embodiments, a dielectric element 124 is formed on thestacked structures 122 similar with the stacked structure 22 shown inFIG. 4, and conductive lines 126 are formed on the dielectric element124 for forming a 3D vertical gate memory device, for example,comprising a NAND flash memory and an anti-fuse memory, etc. Forexample, the silicon-containing conductive structures 118 of differentlayers in the stacked structure 22 act as bit lines (BL) of memory cellsof different planes. The conductive line 126 comprises, for example,polysilicon. The conductive lines 126 may act as word lines (WL), groundselection lines (GSL), or string selection lines (SSL). The dielectricelement 124 may have a multi-layers structure, for example, which may bean ONO composite layers, an ONONO composite layers, or a BE-SONOScomposite layers (referring to U.S. Ser. No. 11/419,977 or U.S. Pat. No.7,414,889), or comprise dielectric layers 128, 130, 132, for example. Inone embodiment, the dielectric layer 128 is silicon oxide, thedielectric layer 130 is silicon nitride, and the dielectric layer 132 issilicon oxide. In other embodiments, the dielectric element 124 is asingle-layer dielectric material (not shown), comprising a siliconnitride, or a silicon oxide such as silicon dioxide or siliconoxynitride.

While the disclosure has been described by way of example and in termsof the exemplary embodiment(s), it is to be understood that thedisclosure is not limited thereto. On the contrary, it is intended tocover various modifications and similar arrangements and procedures, andthe scope of the appended claims therefore should be accorded thebroadest interpretation so as to encompass all such modifications andsimilar arrangements and procedures.

What is claimed is:
 1. A method for manufacturing a semiconductor structure, comprising: forming a first silicon-containing conductive material on a substrate; forming a second silicon-containing conductive material on the first silicon-containing conductive material, wherein the first silicon-containing conductive material and the second silicon-containing conductive material have different dopant conditions; and thermally oxidizing the first silicon-containing conductive material and the second silicon-containing conductive material for turning the first silicon-containing conductive material wholly into an insulating oxide structure, and the second silicon-containing conductive material into a silicon-containing conductive structure and an insulating oxide layer.
 2. The method for manufacturing the semiconductor structure according to claim 1, wherein the first silicon-containing conductive material and the second silicon-containing conductive material have dopants of different concentrations and the same conductivity type.
 3. The method for manufacturing the semiconductor structure according to claim 1, wherein the insulating oxide layer has a bird's beak profile.
 4. The method for manufacturing the semiconductor structure according to claim 1, wherein the insulating oxide structure has a bird's beak profile.
 5. The method for manufacturing the semiconductor structure according to claim 1, wherein the first silicon-containing conductive material and the second silicon-containing conductive material are thermally oxidized simultaneously.
 6. The method for manufacturing the semiconductor structure according to claim 1, wherein during the thermal oxidizing, the first silicon-containing conductive material has an oxide diffusion rate higher than an oxide diffusion rate the second silicon-containing conductive material has.
 7. The method for manufacturing the semiconductor structure according to claim 1, wherein the substrate is single crystal silicon, the first silicon-containing conductive material is single crystal formed from the substrate by an epitaxial growth.
 8. The method for manufacturing the semiconductor structure according to claim 1, wherein the first silicon-containing conductive material is single crystal silicon, the second silicon-containing conductive material is single crystal silicon formed from the first silicon-containing conductive material by an epitaxial growth.
 9. The method for manufacturing the semiconductor structure according to claim 1, wherein the substrate is single crystal silicon, the first silicon-containing conductive material is single crystal silicon formed from the substrate by an epitaxial growth, the second silicon-containing conductive material is single crystal silicon formed from the first silicon-containing conductive material by an epitaxial growth.
 10. The method for manufacturing the semiconductor structure according to claim 1, wherein the first silicon-containing conductive material and the second silicon-containing conductive material are both silicon, the method for manufacturing the semiconductor structure further comprises: before thermally oxidizing the first silicon-containing conductive material and the second silicon-containing conductive material, etching a portion of the first silicon-containing conductive material and the second silicon-containing conductive material for patterning the first silicon-containing conductive material and the second silicon-containing conductive material.
 11. The method for manufacturing the semiconductor structure according to claim 1, wherein a plurality of the first silicon-containing conductive material and a plurality of the second silicon-containing conductive material are formed, the second silicon-containing conductive materials are separated from each other by the first silicon-containing conductive material. 